Pacifiers, clinically termed, “non-nutritive sucking devices,” are nipple substitutes often made of latex rubber or medical grade silicone. Non-nutritive sucking according to the scientific literature involves two factors, creation of suction to hold the device in the mouth and rhythmic jaw movement (nibbling or chewing).
Pacifiers seem to give an awake baby a sense of well-being and comfort. Pacifiers are held in a baby's mouth in a nursing posture. The artificial nipple is positioned against the roof of the mouth and the tongue placed under the nipple in the floor of the mouth. Infants are often put to bed with a conventional pacifier in their mouth.
Nursing and suckling are associated with pacifiers. The term nurse derives from the Latin word “nutrire,” which means, “to nourish.” An accepted dictionary definition of the verb nursing is “being fed at the breast.” The term suckle derives from the old English, and also refers to a baby being fed from the breast or teat. The neurobiology of nursing and suckling consists of the neural coordination of the biologic activities of milk extrusion, sucking, nibbling, swallowing and breathing.
By genetic design, baby humans suckle at their mother's breast to get nutrition. In contemporary culture, however, babies are commonly fed either infant formula or previously pumped breast milk through an artificial nipple. It is not common that babies are fed on their demand at the mother's breast for the entire first two years of their life. Babies are usually fed on a regular schedule, but babies are not always happy with that schedule.
Contrary to common perception, breast feeding is much more complex than just “sucking.” In breast feeding, milk transfer consists of three distinct processes: (1) the baby attaches to the mother's breast by sealing the lips around the breast, the dorsal surface of the tongue pushes the breast to the roof of the mouth and negative pressure of the suction elongates the nipple to approximate the soft palate; (2) rhythmic, positive pressure on the nipple is applied, which is a sort of nibbling movement by the dental ridges (and later the teeth), and is the primary force in releasing milk from the mother's nipple; and (3) positive ductal pressure is applied as a result of the mother's milk ejection reflex.
During breast feeding the baby is simultaneously breathing through the nose, swallowing the milk and not choking. Adults and infants just older than eight months cannot do this. In newborn human babies, whose central nervous system in general is basically quite primitive, this very complex nursing reflex is usually fully developed.
In breast feeding and pacifier use, the main role of suction or negative pressure is to retain the nipple and breast within the baby's mouth. Normal breast feeding is free of frictional movement. If the baby's mouth is sufficiently attached to the mother's breast there is little or no movement of the teat in and out of the baby's mouth. The application of positive rhythmic pressure on the nipple (nibbling) is the main method of milk extrusion in breast feeding.
The perception that bottle feeding only involves suction may, in many cases, also be a misperception. The artificial nipple itself is the determining factor. If the hole in the nipple is too large, as is quite common, the baby's swallowing may be a defense from drowning. When the hole is too large sucking does not occur. If the hole is too small or the nipple is too rigid for the baby to properly constrict it, then nipple compression and sucking result in the milk flowing back into the bottle. It is only with the combination of a properly compliant nipple and the correct hole size in the nipple that suction generated by the baby can be the predominant mechanism for effective milk transfer from bottle to baby.
Pacifiers are commonly thought of as nipple substitutes. Infant pacifiers are technically non-nutritive sucking devices. Pacifiers provide babies with a sense of warmth, security and well-being. With intermittent use during the day non-nutritive sucking devices generally seem to keep babies calm when they would like to feed but it is not on the schedule. Children are often put to sleep with a conventional pacifier in the mouth, especially if they are crying, colicky or otherwise irritable.
Conventional pacifiers may satisfy a baby's inclination for non-nutritive sucking. However, they do not satisfactorily accommodate the anatomy of the human oral cavity and throat, and may not provide preferred positioning for oral development and/or swallowing. Pacifiers that better accommodate the anatomy of the human oral cavity and throat, and/or provide preferred positioning for oral development and/or swallowing, are desirable.